package org.zhadoop.stream.cql.semanticanalyzer.parser.visitor;

import org.antlr.v4.runtime.misc.NotNull;
import org.zhadoop.stream.cql.semanticanalyzer.parser.CQLParser.IdentifierNotContext;
import org.zhadoop.stream.cql.semanticanalyzer.parser.context.NullConditionContext;

/**
 * null condition 语法遍历
 * @author zwd
 *
 */
public class NullConditionVisitor extends AbsCQLParserBaseVisitor<NullConditionContext>{

	private NullConditionContext context = null;
	
	public NullConditionVisitor() {
		context = new NullConditionContext();
	}
	
	@Override
	protected NullConditionContext defaultResult() {
		return context;
	}
	
	@Override
	public NullConditionContext visitIdentifierNot(@NotNull IdentifierNotContext ctx) {
		context.setNot(true);
		return context;
	}
	
}
